1. Technical Field
The present disclosure relates to surgical instrumentation for performing a surgical procedure. More particularly, the present disclosure relates to circular stapling instruments.
2. Background of Related Art
Circular staplers are known, as are their use in procedures in which the stapler is inserted through natural body orifices. Generally, circular staplers are used to provide an anastomosis between two body vessels. Typically the circular staplers include a cartridge assembly on a distal end of an elongate body. The cartridge assembly includes a mechanism for forming staples and a knife for cutting the stapled tissue. Actuation of the cartridge assembly may be performed by a manually operated trigger or a powered drive assembly. Generally, both the actuation of the staple forming mechanism and the advancement of the knife occur at the same time, i.e., simultaneously. Thus, the force provided by the actuation assembly must be sufficient to overcome the force required to form the staples and the force required to advance the knife through the tissue being stapled. Further, the simultaneous actuation of the staple forming mechanism and advancement of the knife requires that the staple forming mechanism and the knife travel the same distance, thereby limiting the staple formation height to the knife travel distance.
Circular staplers which include an anvil assembly having a tilt-able anvil head are well known in the art. In some known circular staplers, tilting anvil mechanisms are spring loaded to tilt to a maximum angle allowed by the circular stapler and/or anvil geometry. Tilting the anvil head to its maximum angle facilitates pulling the anvil head through the area in which the body vessels have been joined in an anastomosis ring.
In forming the anastomosis, the knife of the circular stapler cuts away a donut of tissue. In certain instances, however, the anastomosis donut, the remaining tissue severed from the anastomosis by an annular knife, may become pinched by the anvil head when the anvil head is tilted and thus inhibit full tilting of the anvil head. As a result, the anvil head may contact an edge of the anastomosis ring during withdrawal, which, in turn, may cause unwanted tissue damage (i.e., damage to the anastomosis ring) and/or may result in higher retraction forces being necessary during removal of the anvil head through the anastomosis ring.
Therefore, it would be beneficial to have a circular stapler including a cartridge assembly configured to form staples independently of cutting tissue. It is also desirable to retain the anastomosis donut in a manner that avoids interference between the anvil head of the stapler and donut.